Monday, June 25, 2012

Excerpted from "The Culture of the Grape, and Wine-Making", Seventh Edition, by Robert Buchanan, Cincinnati OH, 1861.

This being the season of the year when the wine may require attention, the reasons for racking and the manner of effecting it are presented :

This operation is performed to separate the wine from its ferment, in order to prevent further change, either spiritous or acetous — to separate it also from the lees, containing, beside the yeast, cream of tartar, and coloring matter which has accumulated at the bottom of the cask. This process also enables us to avoid the exposure of the surface of the wine to the influence of the air, by which it would suffer more evaporation and be liable to be covered with mould, a white cryptogamic plant which covers the wine and gives it a putrid taste.

To effect the first object, frequent racking is required, say 1st, at the end of December ; 2nd, at the end of February, in March or early April; and then again in the autumn, at the end of October : such is my treatment of the Catawba wine during the first year ; after this, it is only racked in the fall. The latter object is to be attained by keeping the cask always bung full to exclude the air arid prevent alcoholic evaporation or absorption of air, to produce putrefaction.

The bung should be made of clear wood, wrapped with clean linen to insure tightness; a caution should however be had to loosen the bungs in April, when the wine is apt to undergo a fermentative change, and should the bung be too tight, so that the gases cannot drive it out, the bottom of the barrel may have to yield before the pressure, and thus the wine will be lost.

In racking, the first requisite is a good wine-green cask, which has previously contained similar wine; it should be carefully examined to ascertain that it is quite clean and has neither a sour nor other bad smell. After the cask is thoroughly rinsed with clear, fresh water, burn a piece of brimstone paper, one by three inches large, suspended from the bung by a piece of bent wire. This is made by dipping paper into melted sulphur. Then fill the cask, but endeavor to expose the wine as little as possible to the air. Never use a new cask in this process, as the wine will acquire a bad smell and taste from the fresh wood. Neither should you think of taking a barrel that has contained brandy, Madeira, or other wine than good Catawba, as these substances always impart a taste to the wine, and thus destroy the fine flavor of our delicate product.

Casks become what is called wine-green, or fit for old wine, after having had fermented in them sweet cider or grape must.

Empty casks may be kept in good order by being thoroughly cleaned, and after they have been left to dry for a few days, burn a piece of sulphur paper and bung them tightly, this may be repeated every three or four months. The burning sulphur produces sulphurous acid gas, which prevents putrefaction and acidulation, but they should be well rinsed before they are again used.

Special caution is given after racking the wine to keep the cask always bung-full; this requires frequent examination, cay every three or four weeks, when it should be filled up. In a cask that is not kept full, there is more evaporation, and in presence of the atmospheric air, acetous or vinegar fermentation is apt to be commenced, the white mould formed, and the wine is spoiled, never to be restored.

A great many persons believe that the racking of wine is not necessary, they say that it is thereby weakened, because the yeast and all the sedimentary matters gives strength to the wine. The temperature of the must during the first week of the first or quick fermentation is very much increased, the liquid from being clear, becomes turbid, owing to the separation and precipitation of the decomposed and effete ferment, the cream of tartar and other matters which are kept in continual motion by the escaping carbonic acid gas. In the second week the fermentation is moderated, the temperature is reduced; in the third week this reduction is still more observable, and fermentation nearly ceases, until the temperature becomes almost the same as the surrounding air, and cold weather comes on. At the end of December the wine will be nearly clear, and this is the time I recommend for the first racking.

At the end of February, the weather is still colder, and more of these foreign ingredients are separated, hence this period is recommended for the second racking, the wine will then be mellow and nearly clear.

In the middle of April, when the vines begin to push forth their buds, the wine ferments again, but if it has been well racked, it possesses little yeast, and the fermentation will be slow, and more of the sugar will be retained in an unchanged condition, so that the wine is more palatable.

What happens, on the contrary, with wines that have not been racked? With the increasing temperature of the season, in April or May, fermentation commences, and the escaping carbonic gas stirs up all the sediment from the bottom of the cask, bringing it into contact with the wine, which retains a portion of what it had before thrown off, the yeast also, thus mixed, will decompose more sugar, and the result will be a too hard and too astringent wine, that must require years to
render it again mellow.

Thursday, June 14, 2012

The following is excerpted from "Manual of American Grape-Growing", 1919, by U. P. Hedrick, and gives a good general overview of the basic steps in the process of wine-making used in the United States around the turn of the 20th century.

There are four distinct stages in the making of wine after the grapes are grown.

The first is the harvesting of the grapes when they have reached the proper stage of maturity, which is known as "wine-making ripeness." This stage of ripeness is determined by means of a must-scale or saccharometer. The wine-maker squeezes the juice from a number of bunches of grapes into a receptacle into which he drops the must-scale, whereupon the sugar-content of the juice is indicated on the scale, determining whether the proper stage of ripeness has been reached. Suitable varieties of grapes having been grown, it is necessary that they be permitted to hang on the vine until the proper degree of ripeness is developed, after which they are delivered at the winery as free as possible from injury or decay.

The second stage is the preparation of the grapes for fermentation. The grapes are weighed on arriving at the winery and are then conveyed either by hand or more often by a mechanical conveyor to the hopper or crusher. The ancient method of crushing, which still prevails in some parts of Europe, was to tramp the grapes with bare feet or wooden shoes. Tramping has been superseded by mechanical crushers which break the skin but do not crush the seeds. The best mechanical crushers consist of two-grooved revolving cylinders. As the grapes pass through the crusher, they fall into the stemmer, a machine which tears off the stems, discharging them at one end, while the seeds, skins, pulp and juice pass through the bottom to the presses usually on the floor below. There are several types of wine-presses, all of which, however, are modifications of screw, hydraulic or knuckle-joint power. In large wineries, the hydraulic press has almost driven out the other two forms of power and when great quantities of grapes must be handled a number of hydraulic presses are usually in operation. The grape pomace is built up into a "cheese" by the use of cloths and racks variously arranged. The "cheese" is then put under heavy pressure from which the juice or "must" is quickly extracted.

The third stage is fermentation. The "must" is carried from the press into open tanks or vats which hold from 500 to 5000 gallons or even more. The yeast cells which cause fermentation may be introduced naturally on the skins of the grapes; or in many modern wineries the "must" is sterilized to rid it of undesirable micro-organisms and a "starter" of "wine-yeast" is added to start the fermentation. Yeast organisms attack the sugar and must, breaking it up into alcohol and carbonic acid gas, the latter passing off as it is formed. When active fermentation ceases, the new wine is drawn from the pomace and is put into closed casks or tanks where it undergoes a secondary fermentation, much sediment settling at the bottom of the cask. To rid the new wine of this sediment, it must be drawn off into clean casks, an operation called "racking." The first racking usually takes place within a month or six weeks. A second racking is necessary at the end of the winter and a third is desirable in the summer or fall.

The fourth stage is the aging of the wine. Before aging begins, however, the wine usually must be rendered perfectly clear and bright by "fining." The materials used in fining are isinglass, white of egg or gelatine. These, introduced into the wine, cause undissolved matters to precipitate. The wine is now ready for bottling or consumption. Most wines acquire a more desirable flavor through "aging," a slow oxidation in the bottles.